1. Technical Field
The present invention relates to an aqueous ink composition, an ink set, and an image forming method.
2. Description of the Related Art
Since image forming methods using an ink-jet method allow, for example, recording of high-quality images on various kinds of recording media by ejecting droplets of inks from nozzles provided at an ink-jet head, such image forming methods are expected to be applied to a wide range of fields.
In the case of forming an image, besides qualities such as the resolution or color tone of the formed image, image density and texture, in terms of image qualities, it is required that unevenness such as streak-like unevenness or regions missing color do not occur in the image and that the image itself is strong against abrasion. Further, in order to realize the high quality that is required as an image, it is also important that the ejection property is satisfactory in the case of ejecting inks from the ejection head.
For example, froth the viewpoint of improving the strength of the formed image or the like, there are cases in which a resin component is present in the ink. In such cases, after ejecting the ink and forming an image, by subjecting the image to a heat treatment, the resin component in the image is softened and forms a film, whereby fixation is conducted, and thus, resistance to external forces such as abrasion can be imparted.
In connection with the technique of using a resin composition, for example, an aqueous ink composition for ink-jet recording containing self-dispersing resin particles together with a pigment, a solvent, and the like has been disclosed (see, for example, Japanese Patent No. 4625133), and it is said that such an ink composition is effective in reducing image blocking and offset at the time of fixation.
Further, as an aqueous ink composition having excellent ejection stability, a composition including a dispersion containing a pigment that is included in a dispersion polymer such that the pigment can be dispersed in water, a wetting agent, and water has been disclosed, and it is described that the composition includes, as the wetting agent, an acetylene glycol surfactant or an acetylene alcohol surfactant, in order to maintain adequate surface tension or adequate interface tension to the head nozzle (see, for example, Japanese Patent Application Laid-Open (JP-A) No. 2010-222418).